Lowestoft and Great Yarmouth regional Astronomers based in Lowestoft and Kessingland Astronomy group which is part of Lyra based in Kessingland

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Monday, 26 May 2014

SPA ENB No. 376

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 376 2014 May 25

Here is the latest round-up of news from the Society for Popular Astronomy. The SPA is Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online atour secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/

ASTRONOMERS FIND SUN'S SIBLINGUniversity of Texas at Austin

A team of researchers has identified the first 'sibling' of the Sun-- a star that was almost certainly born from the same cloud of gasand dust as our star. It is called HD 162826, a star 15% more massivethan the Sun, located 110 light-years away in the constellationHercules. The star is not visible to the unaided eye, but can easilybe seen with low-power binoculars, not far from Vega. The teamidentified HD 162826 as the Sun's sibling from among 30 candidatesfound by several groups around the world looking for solar siblings.It studied 23 of those stars by high-resolution spectroscopy with the107-inch telescope at McDonald Observatory, and the remaining stars(visible only from the southern hemisphere) with the Clay MagellanTelescope at Las Campanas Observatory in Chile. In addition tochemical analysis, the team also included information about the stars'orbits -- their paths around the centre of the Milky Way galaxy.Combining information on both chemical make-up and dynamics of thecandidates narrowed the field down to one: HD 162826. By coincidence,that star has been studied by the McDonald Observatory Planet Searchteam for more than 15 years. The studies have ruled out any 'hotJupiters' -- massive planets orbiting close to the star -- andindicate that it is unlikely that a Jupiter analogue orbits the star,either, but they do not rule out the presence of smaller terrestrialplanets.

While the finding of a single solar sibling is intriguing, the projectis also a preparatory exercise in how to identify solar siblings, inpreparation for the flood of data expected soon from surveys likeGaia. The idea is that the Sun was born in a cluster with a thousandor a hundred thousand stars, which formed more than 4500 million yearsago and has since broken up. The member stars have dispersed intotheir own orbits around the Galactic Centre, taking them to differentparts of the Milky Way today. A few, like HD 162826, are stillnearby. The data coming soon from Gaia are not going to be limited tothe solar neighbourhood since Gaia will provide accurate distances andproper motions for a (US) billion (10*9) stars, allowing astronomersto search for solar siblings all the way to the centre of our Galaxy.The number of stars that we can study will increase by a factor of10,000. Astronomers can concentrate on certain key chemical elements,ones whose abundances vary greatly among stars which otherwise havevery similar chemical compositions and depend on where in the Galaxythe star formed. The team has identified the elements barium andyttrium as particularly useful. Once many more solar siblings havebeen identified, astronomers will be one step closer to knowing whereand how the Sun formed. To reach that goal, the dynamics specialistswill try to make models that run the orbits of solar siblings backwardin time, to find where they intersect: their birthplace.

Jupiter's Great Red Spot -- a swirling anticyclonic storm featurelarger than the Earth -- has shrunk to the smallest size evermeasured. Astronomers have followed its shrinkage since the 1930s.Historic observations as far back as the late 1800s gauged the GRS tobe as much as 25,500 miles on its long axis. The Voyager 1 andVoyager 2 flybys of Jupiter in 1979 measured it at 14,500 milesacross. Starting in 2012, amateur observations revealed a noticeableacceleration in the spot's shrinkage rate. The GRS's 'waistline' isgetting smaller by 580 miles per year and is now 10,250 miles. Theshape of the GRS has changed from an oval to a circle. The cause hasyet to be explained. In new observations it is apparent that verysmall eddies are feeding into the storm, and astronomers hypothesizethat they may be responsible for the sudden change by altering theinternal dynamics and energy of the Great Red Spot. Researchers planto study the motions of the small eddies and also the internaldynamics of the GRS to determine if the eddies can feed or sapmomentum entering the upwelling vortex.

LENGTH OF EXOPLANET DAY MEASUREDESO

Observations from the Very Large Telescope (VLT) have, for the firsttime, determined the rotation rate of an exoplanet, from therotational broadening of its spectral lines. The planet orbits thenaked-eye star Beta Pictoris, which lies about 63 light-years from theEarth in the southern constellation Pictor. It was discovered nearlysix years ago and was one of the first exoplanets to be directlyimaged. It orbits its host star at a distance of eight times theEarth-Sun distance, making it the closest exoplanet to its star to bedirectly imaged. Its equator is moving at almost 100 000 km/h. Forcomparison, Jupiter's equator has a speed of about 47 000 km/h, whilethe Earth's is only 1700 km/h. Beta Pictoris b is more than 16 timeslarger and 3000 times more massive than the Earth, yet a day on theplanet lasts only 8 hours.

It is not known why planets spin at different rates, but this firstmeasurement of an exoplanet's rotation is consonant with the trendseen in the Solar System, where the more massive planets spin faster.Beta Pictoris b is a very young planet, only about 20 million yearsold (compared to 4.5 billion years for the Earth). Over time, theexoplanet is expected to cool and shrink, which will make it spin evenfaster. On the other hand, other processes might be at play thatchange its spin. For instance, the spin of the Earth is slowing downowing to tidal interaction with the Moon.

NEAREST 'HYPER-VELOCITY STAR' FOUND University of Utah

Astronomers have discovered a 'hyper-velocity star' that is theclosest, second-brightest and among the largest of 20 found so far.Hypervelocity stars appear to be former components of binary starsthat once orbited each other but got too close to the supermassiveblack hole at the Galaxy's centre. The gravity of the black hole --which has the mass of 4 million Suns -- captures one star so it orbitsthe hole closely, and ejects the other on a trajectory headed beyondthe Galaxy. The new hypervelocity star was discovered with the 'LargeSky Area Multi-Object Fibre Spectroscopic Telescope, or LAMOST,located at the Xinglong Observing Station of the National AstronomicalObservatories of China, about 110 miles northeast of Beijing. LAMOSThas a 7-m aperture and has 4,000 optical fibres, which capturespectra of as many as 4,000 stars at once. The star -- namedLAMOST-HVS1 -- stood out because its speed is about 600 km/s relativeto the Solar System (500 km/s with respect to the centre of the MilkyWay). Despite being the closest hypervelocity star, it is nonetheless13 kpc (42,000 light years) from the Earth. It has a magnitude ofabout 13, and is nine times the mass of the Sun, rather less thananother hypervelocity star, HD 271791, which was discovered in 2008and is 11 times the mass of the Sun. As seen from the Earth, amongthe hypervelocity stars only HD 271791 is brighter than LAMOST-HVS1.A cluster of known hypervelocity stars, including the new one, is located above the disc of our Milky Way galaxy, and their distributionin the sky suggests that they originated near the Galaxy's centre.

MAGNETAR FORMATION SOLVED? ESO

Magnetars are the bizarre super-dense remnants of supernovaexplosions. They are the strongest magnets known in the Universe --millions of times more powerful than the strongest magnets on Earth.A team of astronomers using the Very Large Telescope (VLT) nowbelieves it has found the partner star of a magnetar for the firsttime. The discovery helps to explain how magnetars form -- aconundrum dating back 35 years -- and why that particular star did notcollapse into a black hole as astronomers might expect. When amassive star collapses under its own gravity during a supernovaexplosion it forms either a neutron star or black hole. Magnetars arean unusual form of neutron star. They are tiny and extraordinarilydense -- a teaspoonful of neutron-star material would have a mass ofabout a billion tons -- but they also have extremely powerfulmagnetic fields. Magnetar surfaces release vast quantities of gammarays when they undergo a sudden adjustment known as a starquake as aresult of the huge stresses in their crusts.

The Westerlund 1 star cluster, 16 000 light-years away in the southernconstellation of Ara, hosts one of the two dozen magnetars known inthe Milky Way. It is called CXOU J164710.2-455216 and it has greatlypuzzled astronomers. Earlier work showed that it must have been bornin the explosive death of a star about 40 times as massive as the Sun.But that presents its own problem, since stars so massive are expectedto collapse to form black holes after their deaths, not neutron stars.Researchers did not understand how it could have become a magnetar. A possible solution was that the magnetar formed through theinteractions of two very massive stars orbiting one another in abinary system so compact that it would fit within the orbit of theEarth around the Sun. But, up to now, no companion star was detectedat the location of the magnetar in Westerlund 1, so astronomers usedthe VLT to search for it in other parts of the cluster. They huntedfor runaway stars -- objects escaping the cluster at high velocities-- that might have been ejected by the supernova explosion that formedthe magnetar. One star, known as Westerlund 1-5, was found to bedoing just that. Not only does it have the high velocity expected ifit is recoiling from a supernova explosion, but the combination of itslow mass, high luminosity and carbon-rich composition appearimpossible to replicate in a single star -- a 'smoking gun' thatsuggests that it must have originally formed with a binary companion.

That discovery allowed the astronomers to reconstruct the stellar lifestory that permitted the magnetar to form, in place of the expectedblack hole. In the first stage of that process, the more massive starof the pair begins to run out of fuel, transferring its outer layersto its less massive companion (which is destined to become themagnetar), causing it to rotate more and more quickly. Rapid rotationappears to be the essential ingredient in the formation of themagnetar's ultra-strong magnetic field. In the second stage, as aresult of the mass transfer, the companion itself becomes so massivethat it in turn sheds a large amount of its recently-gained mass. Muchof that mass is lost but some is passed back to the original star thatwe still see shining today as Westerlund 1-5. It is that process ofswapping material that has imparted the unique chemical signature toWesterlund 1-5 and allowed the mass of its companion to fall to lowenough levels that a magnetar was born instead of a black hole. Itseems that being a component of a double star may therefore be anessential ingredient in the recipe for forming a magnetar. The rapidrotation created by mass transfer between the two stars appearsnecessary to generate the ultra-strong magnetic field and then asecond mass-transfer phase allows the magnetar-to-be to slim downsufficiently so that it does not collapse into a black hole at themoment of its death.

ENTIRE STAR CLUSTER THROWN OUT OF ITS GALAXYHarvard-Smithsonian Center for Astrophysics

The galaxy M87 has thrown an entire star cluster towards us at morethan 1000 km/s. Astronomers have found runaway stars before, but thisis the first time they have found a runaway star cluster. The newlydiscovered cluster has been named HVGC-1; the acronym stands for'hypervelocity globular cluster'. Globular clusters are relics of theearly Universe. Such groupings usually contain thousands of starscrammed into a ball a few dozen light-years across. The Milky Waygalaxy has about 150 globular clusters, but the giant ellipticalgalaxy M87 has thousands. It took a stroke of luck to find HVGC-1.The discovery team has been studying the space around M87. It firstsorted objects by colour to separate stars and galaxies from globularclusters. Then it used the Hectospec instrument on the MMT in Arizonato examine hundreds of globular clusters in detail. A computerautomatically analyzed the data and calculated the speed of everycluster. Any oddities were examined by hand and most of them turnedout to be glitches, but HVGC-1 was different -- its surprisingly highvelocity was real.

Astronomers are not sure how HVGC-1 was ejected at such a high speedbut say that one scenario depends on M87 having a pair of supermassiveblack holes at its core. The star cluster passed too close to thoseblack holes. Many of its outer stars were plucked off, but the densecore of the cluster remained intact and was flung away at tremendousspeed. HVGC-1 is moving so fast that it will escape from M87altogether. In fact, it may have already left the galaxy and besailing out into intergalactic space.

NEARBY GALAXY IS A 'FOSSIL' FROM THE EARLY UNIVERSECarnegie Institution

A team of scientists has analyzed the chemical elements in the faintgalaxy called Segue 1, and determined that it is effectively a fossilgalaxy left over from the early Universe. Astronomers hoping to learnabout the first stages of galaxy formation after the Big Bang use thechemical compositions of stars to help them unravel the histories ofthe Milky Way and other nearby galaxies, and were able to categorizeSegue 1's uniquely ancient composition. Stars form from gas clouds,and their composition mirrors the chemical composition of the gas fromwhich they were born. Only a few million years after stars beginburning, the most-massive stars explode in titanic blasts calledsupernovae. Those explosions seed the nearby gas with heavy elementsproduced by the stars during their lifetimes. The very oldest starsconsist almost entirely of the two lightest elements, hydrogen andhelium, because they were born before ancient supernova explosionsbuilt up significant amounts of heavier elements. In most galaxies,the process is cyclical, with each generation of stars contributingmore heavy elements to the raw material from which the next set ofstars will be born. But not in Segue 1 -- in contrast to all othergalaxies, the new analysis shows that Segue 1's star formation endedat what would ordinarily be an early stage of a galaxy's development.Segue 1 may have failed to progress further because of its unusuallysmall size.

Research suggests that Segue 1 is the least-chemically-evolved galaxyknown. After the initial few supernova explosions, it appears thatonly a single generation of new stars formed, and then for the last 13billion years the galaxy has not been creating stars. Because it hasstayed in the same state for so long, Segue 1 offers uniqueinformation about the conditions in the Universe shortly after the BigBang. Other galaxies have undergone multiple supernova explosionssince their formation. The first supernovae to blow up, from the mostmassive stars, produce elements like magnesium, silicon, and calcium.Later explosions of smaller stars primarily make iron. Segue 1'suniquely low iron abundance relative to other elements shows that itsstar formation must have stopped before any of the iron-formingsupernovae occurred. Its truncated evolution means that the productsof the first explosions in Segue 1 have been preserved. Intriguingly,very heavy elements like barium and strontium are nearly absent fromSegue 1's stars. The heaviest elements in that galaxy are at thelowest levels ever found, and that gives us clues about what thosefirst supernovae looked like. Studying individual stars in dwarfgalaxies can be difficult, and Segue 1, which orbits our own MilkyWay, is particularly small, containing only about a thousand stars.Just seven stars in the entire galaxy are in the red-giant phase oftheir evolution, making them bright enough for modern telescopes todetect the features astronomers use to measure the abundance of eachchemical element. Three of the seven red giants have heavy-elementabundances more than 3,000 times lower than that of the Sun,highlighting the primitive nature of the galaxy. The team used one ofthe 6.5-m Magellan telescopes in Chile to observe five of the Segue 1stars, while one was studied with the 10-m Keck I telescope in Hawaii.The final star was identified and measured by a competing team usingESO's 8.2-m VLT.

NEW ELEMENT CONFIRMEDScience Daily

The periodic table has been extended, with the announcement of theconfirmation of the yet-to-be-named element 117. In 2010 aUS--Russian collaboration announced that it had produced atoms of anelement with 117 protons, filling a gap that appeared when 118 wasmade four years earlier. However, the International Union of Pure andApplied Chemistry (IUPAC) insists on corroboration by two independentteams before it allows new elements to be added to the Periodic Table,although a temporary name of Ununseptium is in use until confirmationhas been made. It has taken four years, but confirmation appearsfinally to have arrived. The discovery was made by a team at the GSIlaboratory in Germany which fused calcium 48 and berkelium 249. Thatis not easy, because berkelium 249 is both hard to produce insubstantial quantities and has a half life of only 320 days -- lessthan half of any amount produced will still exist a year after it wasmade. By watching the alpha particles emitted, the team concludedthat they were the product of two decay chains, both originating with294117, that is an atom with 117 protons and 177 neutrons. One of thechains included the isotopes 270Db and 266Lr, the latter adding fourneutrons to the previous highest isotope of lawrencium. In generallarge atoms have shorter half lives (they decay more quickly throughradiation) as their masses become greater. However, what are known as'islands of stability' exist, and the authors believe that theone-hour half-life of 270Db marks an important step towards theidentification of even-more-long-lived nuclei of superheavy elements.

The manufacturing process was hardly efficient. More than 1000 atomsof 48Ca, not a common isotope in its own right, were fired at theberkelium to produce just four atoms of 117. Nevertheless it is likelythat element 117 will be accepted. Element 117 is the most recent ofsix elements first announced by the Joint Institute for NuclearResearch in Russia. Of them, 113, 115 and 118 remain unconfirmed,although claims have been made for the first two. Such a small sampledoes not allow us to learn much about the chemistry of element 117.Ununseptium's position in the periodic table places it under thehalogen elemnts such as fluorine and chlorine, but the strong capacityto capture electrons that makes those elements so reactive weakens asone goes down the table, and in fact it is thought if one could everproduce enough 117 to observe chemical interactions it would be morelikely to lose electrons than gain them. The next question is, howcan we create elements 119 and 120? To do that, however, a projectileheavier than 48Ca will need to be found; researchers are working onidentifying the best candidate.

We normally associated strong solar flares with large complex sunspotgroups, but it seems that that is not always so. Two recent X-classflares, one in February (within AR 1990) the other in March (withinAR 2017), appeared in sunspot groups that covered little more than anarea similar to the total of the Earth's surface, which by solarstandards is not large. It seems that part of the reason for somesmaller groups creating such powerful flares is that the points ofopposite magnetic polarity are much closer together in those sunspots,and that can lead to strong flaring activity.

Rotation Nos. 2147 - 2148

There was a slight rise in sunspot activity in March. The MeanDaily Frequency climbed to 5.36 but there was a decrease in theRelative Sunspot Number to 74.98.

WHITE-LIGHT ACTIVITY

There was a scattering of sunspots on view as March began. The threehighly active regions (AR 1981, 1982 and 1984), that had crossed thesolar disc in the last week of February, were nearing the west (W)limb and were far less active. They were accompanied by brightfaculae that showed up well against the slightly darker solar-limbregion. Nearer the Central Meridian (CM) were AR 1987 and 1989 withAR 1992 and 1993 almost on the CM. Meanwhile, on the eastern half ofthe solar disc AR 1990 and 1991 had appeared. You *may* recall thatAR 1990 was the large active sunspot group designated AR 1967 on aprevious appearance, that was responsible for the auroral display seenover many parts of the UK and Europe at the end of February. AR 1991had undergone a resurgence of activity by the 3rd: the leader andfollower spots had grown in size and a small number of spots/pores hadappeared between them. AR 1990 and 1991 were last seen nearing theW limb on the 7th (with AR 1993 further along the limb) surrounded bybright faculae. Further east were AR 1996, a cluster of numeroussmall spots, and towards the E limb some small spots (AR 1998 and2000).

AR 1996 had developed in size as it headed towards the W limb aroundthe 9th and 10th. AR 1998 remained much the same but AR 2000 showedsome development and was followed by some extensive bright faculaenear the E limb. AR 2002 had appeared over the E limb around the 8thand within days had rapidly developed into a highly active region.There were some solar flares but none of the strength expected.Nevertheless, the group with its almost round leader spot was a finesight as it crossed the CM around the 14th. Another round spot,AR 2005, had come over the E limb around the 12th. It was not thatactive but over the next few days it was the most prominent featureon the disc as it passed over the CM and went westwards.

By the 23rd we had another spotted disc. AR 2005 was then close tothe W limb followed by bright faculae, and the two most prominentgroups were AR 2010 (at the CM) and following quite close behindAR 2014, which produced a minor but a long-duration flare that day. Both groups had highly complex magnetic structure according to theSpaceweather.com (www.spaceweather.com) website but as the days passesneither produced the strong flares expected. However, on the 29thAR 2017 produced a brief intense X-Class flare (mostly in theultraviolet it seems) that caused great disturbance to the Earth'supper atmosphere and disrupted the normal propagation of terrestrialradio transmissions for a while.

MDF: 5.36 R: 74.98

H-ALPHA ACTIVITY

The first week of March showed a lot of activity. On the 1st the SElimb and particularly the SW limb showed some intricate prominencesand a dark filament leading to a bright prominence on the NE limb.The following day both the E and W limbs had some attractiveprominences. Plages and filaments were evident around AR 1987, 1990,1991 and 1995. A long dusky filament was also clearly seen on the SW.The 3rd and 4th saw plenty of activity, with plages seen around all ofthe sunspot groups and some quite lengthy filaments; on the SW limbsome extensive prominences were visible. A flare was seen withinAR 1991 at 1024 UT on the 4th; elsewhere there were numerous long andelaborate filaments to be seen and some diverse and complexprominences along the SW and NE limbs.

The 5th saw continued filament activity but not much in the way ofprominences. This seemed to be the trend up until the 10th, whenAR 1996, 1998 and 2002 all showed plages (particularly 2002 which hadsome very bright plages near to it) and conspicuous filament activityextending from the E limb where a group of prominences was located.The 11th was very active with plages around all the sunspot groups andnumerous filaments, one of long and curved appearance on the SW andanother reaching from AR 2002 towards the E limb. We saw some fairlylong filaments on the 15th. On the 21st, when AR 2010 was nearing theCM, all sunspot groups showed plages around or near them, particularlyAR 2010 which was extensive. The E limb showed a large complexprominence. When AR 2010 and 2014 crossed the disc in the last weekof March they both had bright plages around them. There was also along filament in the SW that persisted until it started to fade as itneared the SW limb. A bright eruptive prominence was seen on the NWlimb on the 26th. The 29th saw another burst of plage and filamentactivity over many parts of the disc. The most noticeable prominenceswere on the W limb (near AR 2014) and the E limb.

MDF (P): 8.69

Bulletin compiled by Clive Down

(c) 2014 the Society for Popular Astronomy

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Good Clear Skies
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Astrocomet
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Colin James Watling

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Various Voluntary work-Litter Picking for Parish Council (Daytime) and also a friend of Kessingland Beach (Watchman)
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Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
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Astrocomet

I started in Astronomy in 1997 when the Comet Hale Bopp got me interested in Astronomy and Skywatching, since then I have joined Lyra and have vastly improved my knowledge of this very rewarding science.